In this project, we propose to add the collection of biomarkers of stress and health for children aged 0-17 to an ongoing longitudinal study of children, families, and neighborhoods. The study is the Los Angeles Family and Neighborhood Survey (L.A.FANS), whose design remedies many of the problems that have limited previous research on neighborhood effects, by collecting longitudinal data on neighborhoods, families, adults, and children, and on residential choice and neighborhood change. The first wave (L.A.FANS-1), completed in January 2002, interviewed adults and children living in 3,090 households in a diverse stratified probability sample of 65 neighborhoods throughout Los Angeles County. The second wave (L.A.FANS-2), planned for 2005-2006, has been funded by NICHD and NIA and includes the collection of biomarkers of stress and health for adults in the sample, questionnaire-based data on adults and on children and their caregivers, as well as information on neighborhood social and physical conditions. As part of this project (L.A.FANS-2/CB-for "child biomarkers"), we propose to supplement Wave 2 data collection by undertaking fieldwork to collect similar biomarkers of stress and health for all children aged 0-17 in the sample. Data collection will be conducted simultaneously with the main L.A.FANS-2 survey, which will promote efficiency and reduce costs. These data will provide a major new resource for studying the effects of neighborhood and family environments on children's health and well-being. The specific aims of this project are to: (1) Collect physiological markers of stress, disease, and health, including obesity, cortisol (a stress hormone), blood pressure, C-reactive protein (a marker of acute inflammation), Epstein-Barr virus antibodies (a marker of immune function), cholesterol, diabetes, and pulmonary function for all children in L.A.FANS-2; (2) Produce a well-documented data set from these data which, along with the L.A.FANS-1 and L.A.FANS-2 data, will be placed in the public domain for the research community to use in a variety of analyses; and (3) Provide support to the research community interested in using these data. The child biomarker data collected in L.A.FANS-2/CB as part of this project along with other L.A.FANS data will provide an important new resource for a wide range of researchers to investigate the effects of social factors on children's stress, disease, and health.